The invention relates to a battery module having rechargeable cells having a nominal operating temperature greater than 20° C.
A field of application of the invention is power batteries, such as for example those acting as power source for driving a traction motor drive in electric vehicles. The battery module can of course have other applications, for example powering fixed equipment. These applications to power batteries utilise for example lithium-metal-polymer technology cells.
One of the aims of power batteries is to have the greatest possible energy density. Therefore, lithium-metal-polymer cells made by assembling films enable to obtain energy specific and volumic densities, greater respectively than 100 W·h/kg and 100 W·h/l. Another aim of the power battery industry is to produce battery modules having a long life, given that a long life is a factor for competing with combustion engines in applications to motor vehicles.
In general, the cells concerned by the invention are of the type needing to be heated to their nominal operating temperature by a heating element. In a module, the cells are branched between two external connection terminals. A battery is for example formed from several modules having their connection terminals connected in series.
Cells can be in three states: charge, discharge or regeneration. Cells can be charged by being connected to an adapted external charger. The state of discharge corresponds to the electric current feed to a power consuming device from the cells.
The regeneration state corresponds to the situation in which the power consuming device recharges the cells, such as for example in the case of an electric vehicle when braking, in which an electric regeneration current is supplied from the traction motor drive to the cells of the battery. To preserve the lifetime of the modules and of the battery, respect for certain conditions of use when charging is needed. In fact, due to the fact of large power densities, a very high current charge circulates between the entity forming the charger and the battery module or the battery. Charging the battery or the battery module at a too low temperature substantially favours formation of dendrites in the cells, causing their lifetime to be shortened.
Document WO 99/31 752 describes a battery control system, serving as emergency feed for equipment, such as a computer or telecommunications equipment, normally fed by an electricity distribution network rectifier. Via this control system, the battery is charged from the network rectifier and, in case of disruption to the supply network, is discharged in the equipment. The system comprises a rest mode, in which the voltage of the network rectifier is detected to then pass to cold mode. In cold mode, the system utilises the current supplied by the network rectifier to heat the cells of the battery to a temperature of 60° C. Once this temperature of 60° C. is reached, the system switches to charge mode, in which an interrupter placed between the terminals of the battery and the cells is closed to charge the battery from the network rectifier.
It is understood therefore that most of the time, that is, in the absence of breakdown, such a system is not in discharge, but is always connected to a charging entity. The disadvantage of this system is not to be able to do without an external supply system connected permanently to the battery as entity charging the battery. This system is utilised occasionally in the charge and discharge cycle, that is much less than 1% of the time, and not intensively in charge and in discharge. On the contrary, when the battery is used as the sole and autonomous supply for equipment such as a motor vehicle, the battery modules are subjected to a greater number of constraints due to the larger proportion of charge and discharge cycles, greater than 20% of the time.
This system according to document WO 99/31 752 is therefore poorly suited to use of the battery as the sole and autonomous supply of an equipment such as for example a motor vehicle. Due to its topology this system according to document WO 99/31 752 is not appropriate for placing several battery modules in series.
The aim of the invention is to provide a battery module and a battery which are appropriate for applications where the battery module or the battery is not connected permanently to a charging entity but on the contrary must have substantial discharge autonomy on consumer equipment, which allow control of the process for heating and charging the cells, preservation of the lifetime of the battery module or of the battery, and to keep significant power density in intensive use. To this end, a first subject matter of the invention is a power battery module, comprising a multiplicity of rechargeable cells having a nominal operating charging temperature, greater than 20° C., two external use terminals for using the cells and at least one electric element for heating of the cells,                characterised in that it further comprises a circuit for managing charging of the cells, which comprises:        two external charging terminals for charging of the cells, wherein said two external charging terminals are intended to be connected to an external charger, wherein at least one, called second charging terminal, of the two external charging terminals is distinct from the two external use terminals,        first interruption/connection means between said at least one second charging terminal and at least one of the use terminals, called first use terminal,        the first interruption/connection means being able to be in one or the other of a first interruption position to prevent the flow of current between the second charging terminal and the first use terminal, and of a second connection position for connecting the second charging terminal and the first use terminal,        second linking means between the charging terminals and the heating element to connect, at least in the first interruption position of the first interruption/connection means, the charging terminals to the heating element to supply the heating element with electricity.For example, the two charging terminals are second charging terminals, distinct from the use terminals, called first use terminals, the first interruption/connection means being provided between the second terminals and the first terminals.        
Embodiments of the invention are provided to especially resolve the problems associated with placing several modules in series by their use terminals. In fact, one aim is to provide a battery module which is easy to use and especially can be utilised non-autodestructively in the case of such connecting in series, required for sole and autonomous feed of equipment such as for example a motor vehicle. In this case major technical constraints occur, due to high voltages (several hundreds of volts), which are potentially destructive to the interrupters used in each module.
According to embodiments of the invention:                The second linking means comprise at least one heating interrupter, having an opening and closing control input, in series with the heating element, this series circuit being connected between the charging terminals,        the control input being connected to opening activation means comprising a control input for putting the heating interrupter in an opening position in the presence of an opening control signal on said control input,        third means being provided in the module so that closing of the heating interrupter is independent from the opening activation means and from the control input;        The second linking means comprise at least one heating interrupter, having an opening and closing control input, in series with the heating element, this series circuit being connected between the charging terminals,        the control input being connected to third means for automatic closing activation of the heating interrupter in the presence of voltage between the charging terminals, and to opening activation means comprising a control input for putting the heating interrupter in an opening position in the presence of an opening control signal on said control input;        The control input of the opening activation means is opto-insulated relative to the control input of the heating interrupter;        Or the opening activation means comprise an interrupter, having a principal current interruption/conduction path which is connected in parallel to the series circuit formed by the heating interrupter and the interruption means and having a control terminal serving as opening control input;        The second linking means comprise in series with the heating element at least one heating interrupter, having an opening and closing control input, this series circuit being connected between the charging terminals,        the control input of the heating interrupter being connected to voltage limitation means;        The third means comprise elements for biasing of the control input from the charging terminals;        The voltage limitation means comprise at least one Zener diode;        The heating interrupter comprises at least one transistor, having a principal current interruption/conduction path which is in series with the heating element and having a control terminal for controlling the principal path and serving as control input;        The transistor of the heating interrupter is a MOS transistor, having a drain-source section which forms the principal current interruption/conduction path and having a gate serving as control input;        The Zener diode is in parallel with the gate-source section of the MOS transistor of the heating interrupter;        The second linking means comprise, in series with the heating element between the charging terminals, at least one thermal fuse protecting against temperatures exceeding a preset temperature greater than the nominal operating charging temperature of the cells;        It comprises at least one unit for measuring the temperature in at least one zone of the module, and control means for controlling of the position of the first interruption/connection means,        said control means being sensitive to the temperature measured by the measuring unit in order to operate the first interruption/connection means into the connection position, when the minimal temperature provided by the measuring unit is greater than or equal to the nominal operating charging temperature preset to said control means;        The second linking means comprise at least one heating interrupter, having an opening and closing control input, in series with the heating element, this series circuit being connected between the charging terminals,        the module comprising control means connected to the control input for opening the heating interrupter only when the first interruption/connection means is in the connection position;        The heating element is respectively associated with the temperature-measuring unit in said zone of the module, and        the control means are provided to cause, when of the first interruption/connection means is in the connection position, the heating interrupter to open when the measured temperature of the associated unit becomes greater than a first preset temperature, greater than the nominal operating charging temperature, and to cause the heating interrupter to close when the measured temperature of the associated unit becomes less than a second preset temperature, less than the nominal operating charging temperature and greater than 20° C.;        A temperature-measuring unit is provided in at least two different zones of the module;        The cells are made by assemblies of thin films;        The cells have a nominal operating charging temperature, greater than 80° C.;        The cells are of lithium-metal-polymer type;        It comprises means for producing of a quantitative charging setpoint and a first access for communication to the outside, able to transmit the quantitative charging setpoint.        
A second subject matter of the invention is a battery, characterised in that it comprises a plurality of battery modules as described above in a battery case, the modules being connected by their use terminals in the case, the battery comprising at least two use terminals, accessible outside the case and connected to the modules, and at least two charging terminals, accessible outside the case and connected to the modules. According to other features of the invention:                The use terminals of the modules are connected successively in series in the case, one of the external use terminals is connected to the use terminal of the lowest voltage of all the modules and the other external use terminal of the battery is connected to the use terminal of the highest voltage of all the modules;        The charging terminals of each module are accessible outside the case;        The modules are connected by their charging terminals in the case, the battery comprising two charging terminals, accessible outside the case and connected to the modules;        The charging terminals of the modules are connected successively in series in the case, one of the external charging terminals is connected to the charging terminal of the lowest voltage of all the modules and the other external charging terminal of the battery is connected to the charging terminal of the highest voltage of all the modules;        The battery comprises means for producing of a quantitative charging setpoint of the modules and a first access for communication to the outside, able to transmit the quantitative charging setpoint.        
A third subject matter of the invention is a method for charging a battery module as described above from an external charger, characterised in that                the at least one second external charging terminal is first disconnected relative to the at least one first external use terminal distinct from the at least one second external charging terminal,        the charger is connected to the external charging terminals to apply voltage to it,        the heating element is connected to the external charging terminals to heat the cells of the module from the voltage of the charger at least to the nominal operating charging temperature during an initial heating phase, and        after the initial heating phase, the at least one first external use terminal is connected to the at least one second external charging terminal to charge the cells from the voltage of the charger.        
According to other features of the invention:                The two charging terminals are second charging terminals, distinct from the use terminals, called first use terminals,        before and during the initial heating phase, the two charging terminals are disconnected relative to the use terminals, until the cells are heated to their nominal operating charging temperature,        after the initial heating phase, the cells are charged from the voltage of the charger from the second charging terminals, by connecting the charging terminals to the use terminals;        At least one measuring unit provided in at least one zone of the module measures the temperature,        a calculator of the module, connected to the measuring unit monitors the measured temperature of the cells and cause the connection of the at least one first external use terminal to the at least one second external charging terminal when the minimal measured temperature is greater than or equal to the nominal operating charging temperature;        At least one heating interrupter, comprising an opening and closing control input, is in series with the heating element, this series circuit being connected between the two external charging terminals,        the heating interrupter is automatically closed in the presence of the voltage of the charger on the external charging terminals during the initial heating phase,        a calculator of the module controls the control input to at least temporarily cause opening of the heating interrupter only when the charging terminals are connected to the use terminals;        The heating element is respectively associated with the temperature-measuring unit in said zone of the module, and        when the charging terminals are connected to the use terminals, the calculator controls the control input to cause opening of the heating interrupter when the measured temperature of the associated unit becomes greater than a first preset temperature, greater than the nominal operating charging temperature, and to cause the closing of the heating interrupter when the measured temperature of the associated unit becomes less than a second preset temperature, less than the nominal operating charging temperature and greater than 20° C.;        A temperature-measuring unit is provided in at least two different zones of the module;        The battery module is housed in a motor vehicle.        
A fourth subject matter of the invention is a motor vehicle, comprising a traction motor drive and at least one battery as described above, for at least temporarily supplying the traction motor drive with electric power.